been lurking for a long time, but finally bought a 92 gs500 with 10k miles on it a few days ago. the PO hadn't taken very good care of it and its in a general state of disrepair. bike wouldn't start at all when i got it. dumped the gas tank and found 2 gallons of what was basically mud. cleaned the tank out and then took the carbs apart and cleaned them, jets were clogged with rust. got it all back on the bike and cranked her up, started first try with no choke in 35 degree weather. there was then a mishap with a leaking oil filter plate and broken studs, but we wont go into that...
anyway to get to the point, the bike idles fine, but when you give it gas it will bog down bad at 1500 rpm and die if you dont let off. however, if you really get on the gas it will pass this point and run great to redline. when letting it back down the problem kicks back in at 2000 rpm. thought it must be more junk in the carbs so i took them out and cleaned them again, even though they were still clean. checked the needles and the slides, seem to be working smoothly. some of the gaskets did look just a little old, but none were in bad enough shape for me to say they should be replaced. now, this was my first time working with carbs, so there is a strong possibility that maybe i messed something up and that is whats causing this. for the record, i did get carb cleaner on some of the plastics and the diaphragm, as i wasn't aware that carb cleaner killed plastic until i read it in a thread.
put the carbs back in, same thing.
read some more threads and decided to check if both cylinders were firing. cranked her up and pulled the right plug cap (i know some people say this can ruin coils, but didnt know that at the time) and nothing changed, engine just kept on running, didn't even change sounds. turned the bike off and put the cap back on. i then cranked it back up and pulled the left plug cap and it died instantly. pulled the plugs and tested them by sparking them on the top of the engine, left one has a strong spark, but the right one only sparks every couple times you hit the starter. the right plug was also much whiter than the left. switched the plugs, still acting exactly the same. decided it might by the coils, so i switched the coils, nothing changed.
i'm now at a loss for what to do next, signal generator? take the carbs out again? looking for any kind of advice.
change your plugs
UNSCEW the "boot" from the coil's wire
cut 1/3 an inch off the wire
screw it back on
if that dosnt work
change the coils with each other
if the spark moves to the other cly then you need to order a new coil
that should fix ya right up
Check to see if the coil wire is loose in the coil. These are bonded in and the coil and wire are sold as a unit but they can come loose. I lost one cyl and that was the problem and cutting off the coil end of the wire and screwing it back in fixed it for a while. Later, I put in a new piece of wire and put a big dab of diaelectric grease on the end of the wire for a longer lasting fix after I had to ride it home on one cylinder one wet day. Need a good running start to get a GS500 up even small hills on one cylinder.
A bad pickup coil in the spark generator at the right end of the crankshaft is another possibility, there are seperate pickup coils on the pre 04 GSs. Switching the coils and coil wires betweeen sides is a good check to see if the problem is in the coils or in the pickups.
thanks for the replies. i've already checked the coils by switching them and they aren't the problem. i will try the pickup coils next. cranked it up again last night and i'm beginning to seriously think its a carb issue. some of the o rings probably need to be replaces. is there anywhere i can get o rings for carbs other than a rebuild kit? as in like lowes or the dealer? if i cant get it going soon i'm just gonna break down and send it to the buddha for him to take a look. also, off topic, i just won a sweet 04 gas tank in perfect condition off ebay for 50 bucks, the one that came with the bike is mauled, hoping this one looks good on it.
was just reading about pickups and saw it said they were in the engine assembly, as in like under the suzuki emblems on the tranny? because the PO dropped the bike and it broke off the emblem on the right side, exposing a nut that spins when the bike runs. i know nothing whatsoever about trannys, so this my be something else entirely, just thought it was worth mentioning.
-update-
just checked the signal generators with a ohmmeter set at 20k. both front and back read .28. the number doesn't really mean anything to me, but both readings are the same, so there is nothing wrong with the one for the dead cylinder. i guess check the wiring next? i'm starting to wonder if it isn't electrical, since the plug will spark when the starter is hit, just not quite as often as the one on the right side. could this all be a carb issue?
Quote from: cjones1344 on January 04, 2009, 10:19:43 AM
was just reading about pickups and saw it said they were in the engine assembly, as in like under the suzuki emblems on the tranny? because the PO dropped the bike and it broke off the emblem on the right side, exposing a nut that spins when the bike runs. i know nothing whatsoever about trannys, so this my be something else entirely, just thought it was worth mentioning.
Drop on the right side reminds me of this post: http://gstwins.com/gsboard/index.php?topic=44512.msg498737#msg498737
if your pickups are working and the problem dosnt follow your coils
then 98% chance it's the carbs...
tkae both apart and put them both together
nothing helps a carb like a good ol cleaning
and assuming nothing is broken or lost while you do it
should only cost one or 2 cans of carb clean at 4$ each
you may also have a cracked rummber boot under your carbs CAP
that can cause vaccum issuse and then the slibe wont lift (IIRC)
k gonna give the carbs another, more thorough cleaning tomorrow. planning on replacing a couple of o rings that may be little old. can i get them at a normal hardware store? or am i gonna have to get them from a dealer? also, i know for a fact that one of the diaphragms is a little messed up, its too big to fit perfectly in the groove, though i did manage to get it in there. they're kinda expensive, think its worth replacing?
Quote from: cjones1344 on January 04, 2009, 11:01:37 PM
k gonna give the carbs another, more thorough cleaning tomorrow. planning on replacing a couple of o rings that may be little old. can i get them at a normal hardware store? or am i gonna have to get them from a dealer? also, i know for a fact that one of the diaphragms is a little messed up, its too big to fit perfectly in the groove, though i did manage to get it in there. they're kinda expensive, think its worth replacing?
For convenience, I buy the o-rings at the dealer. However, many members have reported finding them at local hardware stores without trouble (ACE, etc).
You could also ask The Buddha about o-rings. He will likely have the diaphragms too.
http://gstwins.com/gsboard/index.php?topic=40688.0
you can get O-rings anywhere but make sure thay can withstand gas (as many cant)
i notmally get then from the auto parts store
and if you know your rubber diaphram isnt right then you already know your problem.
I bought a box of metric nitrile o-rings at Harbor Freight for "super cheap get what you pay for." Anyway, based on my theory of believing everything I read on the internet, I found that nitrile withstands fuel well and is suited for the carb. One of the various sizes in the box fit the main jet,
edit: or was it the pilot jet? can't remember.
and that was the only one that I tried, and it works, and I have over two weeks of use so far!!
Argh, I don't know what I'm doing.
Clogged pilot jet is my bet. You're bogging to 1500, past it it revs, that rules out the crank trigger.
Cool.
Buddha.
could this also be REALLY rich mix-screw setting? Like over 3-turns out?